A wireless charging device, a receiver device, and an associated method thereof

ABSTRACT

A wireless charging device (102) is disclosed. The wireless charging device (102) includes a transmitter detection coil (130) configured to receive a first alternating current (AC) voltage signal having a characteristic associated with a receiver device (104). Also, the wireless charging device (102) includes a control unit (112) coupled to the transmitter detection coil (130) and configured to detect the receiver device (104) based on the characteristic of the first AC voltage signal. Further, the wireless charging device (102) includes a driver unit (108) coupled to the control unit (112) and configured to convert a direct current (DC) voltage signal of an input power to a second AC voltage signal if the receiver device (104) is detected. In addition, the wireless charging device (102) includes a power transmission coil (116) configured to wirelessly transmit the second AC voltage signal to the receiver device (104).

BACKGROUND

Embodiments of the present invention relate generally to wireless powersystems and more particularly to wireless charging device, a receiverdevice, and an associated method thereof.

In general, power transfer systems are used to transfer electric powerfrom a power source to one or more receiver devices, such as forexample, mobile devices, biomedical devices, and portable consumerdevices. The power transfer systems are contact based power transfersystems or wireless power transfer systems. A contact based powertransfer system includes interconnecting wires used to transfer electricpower from the power source to receiver devices. Such interconnectingwires may damage or corrode over a period of time. Further,interconnecting wires of a contact based power transfer systemcontributes to the overall weight of the system. Wireless power transfersystems may be desirable to transfer power from a power source toreceiver devices.

Typically, in a conventional power transfer system, a charging device isused to convert an input electric power received from a power source toa transferrable electric power that is transmitted to charge one or morebatteries in a receiver device. However, the charging device maycontinuously transmit the power even if the receiver device is notpresent. Such transmission of power results in power loss and affectsefficiency of the charging device.

Therefore, there is a need for an enhanced wireless charging device, areceiver device, and a method for detecting receiver devices.

BRIEF DESCRIPTION

In accordance with one embodiment of the present invention, a wirelesscharging device is disclosed. The wireless charging device includes atransmitter detection coil configured to receive a first alternatingcurrent (AC) voltage signal having a characteristic associated with areceiver device. Also, the wireless charging device includes a controlunit coupled to the transmitter detection coil and configured to detectthe receiver device based on the characteristic of the first AC voltagesignal. Further, the wireless charging device includes a driver unitcoupled to the control unit and configured to convert a direct current(DC) voltage signal of an input power to a second AC voltage signal ifthe receiver device is detected. In addition, the wireless chargingdevice includes a power transmission coil coupled to the driver unit andconfigured to wirelessly transmit the second AC voltage signal to thereceiver device.

In accordance with another embodiment of the present invention, areceiver device is disclosed. The receiver device includes a signalgenerating unit configured to generate a first alternating current (AC)voltage signal having a characteristic associated with the receiverdevice. Also, the receiver device includes a receiver detection coilcoupled to the signal generating unit and configured to transmit thefirst AC voltage signal having the characteristic to a wireless chargingdevice. Further, the receiver device includes a power reception coilconfigured to be magnetically coupled to the wireless charging deviceand receive input power having a second AC voltage signal in response totransmitting the first AC voltage signal to the wireless chargingdevice.

In accordance with another embodiment of the present invention, a methodfor detecting a receiver device is disclosed. The method includesgenerating, by a signal generating unit, a first alternating current(AC) voltage signal having a characteristic associated with a receiverdevice. Also, the method includes transmitting, by a receiver detectioncoil, the first AC voltage signal having the characteristic to awireless charging device. Further, the method includes receiving, by apower reception coil, input power having a second AC voltage signal inresponse to transmitting the first AC voltage signal to the wirelesscharging device.

In accordance with another embodiment of the present invention, awireless power transfer system is disclosed. The wireless power transfersystem includes at least one receiver device including a signalgenerating unit configured to generate a first alternating current (AC)voltage signal having a characteristic associated with the at least onereceiver device. Also, the at least one receiver device includes areceiver detection coil coupled to the signal generating unit andconfigured to transmit the first AC voltage signal having thecharacteristic to a wireless charging device. Further, the wirelesspower transfer system includes the wireless charging device wirelesslycoupled to the at least one receiver device and including a transmitterdetection coil configured to receive the first alternating current (AC)voltage signal having the characteristic associated with the receiverdevice. Also, the wireless charging device includes a control unitcoupled to the transmitter detection coil and configured to detect thereceiver device based on the characteristic of the first AC voltagesignal.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 a block diagram of a wireless power transfer system in accordancewith an embodiment of the present invention;

FIG. 2 is a detailed schematic representation of a wireless powertransfer system in accordance with an embodiment of the presentinvention;

FIG. 3 is a flow chart illustrating a method for indicating a presenceof a receiver device and receiving electric power from a wirelesscharging device in accordance with embodiments of the present invention;and

FIG. 4 is a flow chart illustrating a method for detecting a receiverdevice in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

As will be described in detail hereinafter, various embodiments of asystem and a method for charging one or more receiver devices aredisclosed. In particular, embodiments of the system and the methoddiscloses detection of the receiver device prior to transmittingelectric power to the receiver device. Additionally, the embodiments ofthe system and the method discloses detection of one or more foreignobjects.

Unless defined otherwise, technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art to which this specification belongs. The terms “first”,“second”, and the like, as used herein do not denote any order,quantity, or importance, but rather are used to distinguish one elementfrom another. The use of terms “including,” “comprising” or “having” andvariations thereof herein are meant to encompass the items listedthereafter and equivalents thereof as well as additional items. Theterms “connected” and “coupled” are not restricted to physical ormechanical connections or couplings, and can include electricalconnections or couplings, whether direct or indirect. Furthermore, terms“circuit” and “circuitry” and “control unit” may include either a singlecomponent or a plurality of components, which are either active and/orpassive and are connected or otherwise coupled together to provide thedescribed function. In addition, the term operationally coupled as usedherein includes wired coupling, wireless coupling, electrical coupling,magnetic coupling, radio communication, software based communication, orcombinations thereof.

FIG. 1 is a diagrammatical representation of a wireless power transfersystem 100 in accordance with an embodiment of the present invention.The wireless power transfer system 100 includes a wireless chargingdevice 102 and a receiver device 104. The wireless charging device 102may include a power transmitting device, such as a power bank, acharging pad, or the like. The receiver device 104 may include a mobiledevice, a biomedical device, a portable consumer device, or the like.For ease of understanding, only one receiver device 104 is depicted inFIG. 1. In other embodiments, the wireless power transfer system 100 mayinclude a plurality of receiver devices that are compatible with one ofthe wireless frequency standards. In one embodiment, the wirelessfrequency standards include a Power Matters Alliance (PMA) standard, anAir Fuel Alliance standard, a Qi standard, a Wireless Planning andCoordination (WPC) standard, and the like.

The wireless charging device 102 is configured to magnetically orwirelessly couple to the receiver device 104 to transmit electricalpower to the receiver device 104. In one embodiment, the electric powermay be in a range from about 0.1 W to about 3000 W. Further, thereceiver device 104 is configured to receive the electric power from thewireless charging device 102 and supply the received electric power toone or more loads, such as batteries in the receiver device 104.

In a conventional power transfer system, a charging device maycontinuously transmit power even if a receiver device is not present ata proximate location, resulting in power loss and thereby affecting theefficiency of the charging device.

The exemplary wireless power transfer system 100 includes detectioncoils 130, 132 in the wireless charging device 102 and the receiverdevice 104 respectively. The detections coils 130, 132 aid in detectingthe receiver device 104 before transmitting the electric power. Thereceiver device 104 may be detected at a location within a predetermineddistance from the wireless charging device 102. In one embodiment, thepredetermined distance may be in a range from about 5 mm to 500 mm. Inparticular, the detection coil 132 in the receiver device 104 transmitsa first AC voltage signal 134 to the wireless charging device 102. Thefirst AC voltage signal 134 is a low voltage signal that is used fordetecting the receiver device 104. In one embodiment, the magnitude ofthe first AC voltage signal 134 is in a range from about 20 V to about30 V. It may be noted herein that the detection coil 132 in the receiverdevice 104 may also be alternatively referred as a “receiver detectioncoil.”

The detection coil 130 in the wireless charging device 102 receives thefirst AC voltage signal 134. It may be noted that the detection coil 130in the wireless charging device 102 is alternatively referred to as a“transmitter detection coil.” Further, the wireless charging device 102detects the presence of the receiver device 104 based on one or morecharacteristics of the received first AC voltage signal 134. In oneembodiment, the characteristics of the first AC voltage signal 134include a frequency and a voltage associated with the receiver device104. In another embodiment, the characteristic of the first AC voltagesignal 134 may be representative of at least one of a frequency and avoltage associated with the receiver device 104. The voltage of thefirst AC voltage signal may be a peak voltage or a root mean square(RMS) voltage. The aspect of detecting the receiver device 104 isexplained in greater detail in the below description.

The wireless charging device 102 includes a power source 106, a driverunit 108, a transmitting unit 110, a control unit 112, a detection unit114, and the transmitter detection coil 130. The power source 106 iscoupled to the driver unit 108 and used to supply input power having aDC voltage signal 118 to the driver unit 108. In some embodiments, theinput power may be in a range from about 0.1 W to 3 KW. The magnitude ofthe DC voltage signal 118 may be in a range from about 20 V to about 500V. It may be noted that the power source 106 may be positioned withinthe wireless charging device 102 or external to the wireless chargingdevice 102.

The driver unit 108 is electrically coupled to the transmitting unit 110and the control unit 112. Further, the driver unit 108 is configured toconvert the DC voltage signal 118 to a second AC voltage signal 136based on one or more control signals received from the control unit 112.The second AC voltage signal 136 is also referred to as a high powersignal that is used for supplying electric power to a load 126, such asone or more batteries in the receiver device 104. In one embodiment, themagnitude of the second AC voltage signal 136 is in a range from about250 V to about 450 V. The second AC voltage signal 136 is generated whenthe wireless charging device 102 is operating in a normal mode/a powertransmission mode.

The transmitting unit 110 is configured to transmit the second ACvoltage signal 136 received from the driver unit 108. In the exemplaryembodiment, the transmitting unit 110 includes a resonant capacitor 115and a power transmission coil 116 that resonates at a predefinedfrequency to transmit the second AC voltage signal 136 to the receiverdevice 104.

The receiver device 104 includes a power reception coil 124, a rectifierunit 128, the load 126, a receiver power source 138, a signal generatingunit 140, the receiver detection coil 132, and a push switch 142. Thepower reception coil 124 is configured to receive the second AC voltagesignal 136 from the power transmission coil 116 of the wireless chargingdevice 102. The rectifier unit 128 is coupled to the power receptioncoil 124 and configured to convert the second AC voltage signal 136 to aDC load signal 144 which is further transmitted to the load 126. In oneexample, this DC load signal 144 may be used for charging the batteriesin the receiver power source 138. In one embodiment, the load 126 andthe receiver power source 138 may be a combined energy storage module.

In addition, the signal generating unit 140 is coupled to the receiverpower source 138 and configured to receive electric power from thereceiver power source 138. The signal generating unit 140 is furtherconfigured to generate the first AC voltage signal 134 based on a biasvoltage 146 received from the receiver power source 138. In oneembodiment, a user may manually switch ON the push switch 142 to send anactivation signal 148 to activate the signal generating unit 140. Uponreceiving the activation signal 148 from the push switch 142, the signalgenerating unit 140 generates the first AC voltage signal 134. It may benoted that the push switch 142 may be positioned internal or external tothe receiver device 104. Further, the receiver detection coil 132 iscoupled to the signal generating unit 140 and used to send the generatedfirst AC voltage signal 134 from the signal generating unit 140 to thewireless charging device 102. It may be noted that although push switch142 is used, in other embodiments, the signal generating unit 140 may beactivated to generate the first AC voltage signal 134 by one or moreother methods and/or devices. In one embodiment, the signal generatingunit 140 may be activated by moving the receiver device 104 along adesired direction and placing the receiver device 104 on the wirelesscharging device 102. In another embodiment, the signal generating unit140 may be activated based on a charge level in the load 126. If thecharge level in the load 126 is less than a desired value, the signalgenerating unit 140 may be activated to generate the first AC voltagesignal 134. In yet another embodiment, the signal generating unit 140may include one or more wireless transceivers that may directly transmitthe first AC voltage signal 134 to the detection unit 114 in thewireless charging device 102, using one or more short rangecommunication techniques, such as Bluetooth and near field communication(NFC).

During operation, the wireless charging device 102 detects the receiverdevice 104 prior to transmitting the power to the receiver device 104.Particularly, when the receiver device 104 is located within thepredetermined distance from the wireless charging device 102, thetransmitter detection coil 130 receives the first AC voltage signal 134from the receiver detection coil 132 of the receiver device 104.Further, the detection unit 114 is coupled to the transmitter detectioncoil 130 and configured to determine one or more characteristics of thereceived first AC voltage signal 134.

Further, the control unit 112 is coupled to the detection unit 114 andconfigured to detect the receiver device 104 based on thecharacteristics of the received first AC voltage signal 134. Morespecifically, if the receiver device 104 is within the predetermineddistance from the charging device 102, the characteristics, such as thefrequency and the voltage of the first AC voltage signal 134 are withincorresponding predefined range. Specifically, the frequency of the firstAC voltage signal 134 is within a predefined frequency range and thevoltage of the received first AC voltage signal 134 is within apredefined voltage range, if the receiver device 104 is within thepredetermined distance from the charging device 102.

When the receiver device 104 is detected, the control unit 112 drivesthe driver unit 108 to transmit the second AC voltage signal 136 via thetransmitting unit 110 to the detected receiver device 104. If thecharacteristics, such as the frequency and the voltage of the first ACvoltage signal 134 are not within the corresponding range, the controlunit 112 determines that the receiver device 104 is not proximate orwithin the predetermined distance from the charging device 102. As aresult, the control unit 112 controls the driver unit to stop thetransmission of the second AC voltage signal 136. The aspect ofdetecting the receiver device 104 is explained in greater detail withreference to FIG. 2.

In one embodiment, the control unit 112 may also be used to detect oneor more foreign objects that are proximate to the wireless chargingdevice 102 based on the frequency and the voltage of the first ACvoltage signal 134. More specifically, if a foreign object is proximateto the wireless charging device 102, the frequency and voltage of thefirst AC voltage signal 134 may be within a different range. The valuesof the frequency and voltage enables to determine that the object thatis proximate to the wireless charging device 102 is a foreign object andnot the receiver device 104. Thus, by employing the exemplary wirelesscharging device 102, the input power may be wirelessly transmitted afterdetecting the receiver device 104, which in turn reduces power loss inthe wireless power transfer system 100 and thereby improve theefficiency of the wireless charging device 102. Further, the exemplarysystem and method facilitate to reduce electromagnetic interference(EMI) and thereby meet regulatory standards.

Referring to FIG. 2, a schematic representation of a wireless powertransfer system 100 in accordance with the embodiment of FIG. 1. Thewireless power transfer system 100 includes the wireless charging device102 that is configured to be magnetically coupled to the receiver device104.

The receiver detection coil 132 in the receiver device 104 ismagnetically coupled to the transmitter detection coil 130 of thewireless charging device 102 if the receiver device 104 is locatedwithin a predetermined distance from the wireless charging device 102.Further, the signal generating unit 140 is configured to generate thefirst AC voltage signal 134 based on the DC voltage 146 received fromthe receiver power source 138 in the receiver device 104. In oneembodiment, the DC voltage 146 is used as a bias voltage for the signalgenerating unit 140 to generate the first AC voltage signal 134. In theillustrated embodiment, the signal generating unit 140 includes avoltage controlled oscillator (VCO) 202, a signal controller 204, and abuffer unit 206. The VCO 202 is electrically coupled to the signalcontroller 204 and the buffer unit 206. The VCO 202 is pre-tuned ordesigned to oscillate at a first frequency that is associated with thereceiver device 104. Further, the signal controller 204 activates theVCO 202 when the activating signal 148 is received. Upon activating theVCO 202, the VCO 202 receives the bias or DC voltage 146 from thereceiver power source 138 and oscillates at the first frequency toconvert the received bias or DC voltage 146 to the first AC voltagesignal 134 having the first frequency. The buffer unit 206 is used tostep-up the power level of the first AC voltage signal 134 beforetransmitting the first AC voltage signal 134 to the receiver detectioncoil 132.

In one embodiment, the user presses the push switch/button 142 that iscoupled to the signal generating unit 140, to transmit the activatingsignal 148 to activate the signal generating unit 140 to generate thefirst AC voltage signal 134. In one embodiment, the activating signal148 is transmitted to the signal controller 204 in the signal generatingunit 140. It may be noted that although push switch/button 142 is used,in other embodiments, the signal generating unit 140 may be activated byone or more other type of devices.

Further, the signal generating unit 140 transmits the first AC voltagesignal 134 to the wireless charging device 102 via the receiverdetection coil 132. In particular, the receiver detection coil 132 ismagnetically coupled to the transmitter detection coil 130 to transmitthe first AC voltage signal 134 to the transmitter detection coil 130.Further, the detection unit 114 that is coupled to the transmitterdetection coil 130, receives the first AC voltage signal 134 from thetransmitter detection coil 130. The detection unit 114 determines one ormore characteristics of the first AC voltage signal 134. In oneembodiment, the characteristics of the first AC voltage signal 134includes a frequency and a voltage, such as peak voltage and root meansquare (RMS) voltage of the first AC voltage signal 134. In oneembodiment, the detection unit 114 measures a voltage drop across thetransmitter detection coil 130. The voltage drop may be referred to asthe voltage of the first AC voltage signal 134. The detection unit 114includes a frequency counter 208 and a peak detector 210 that areelectrically coupled to the transmitter detection coil 130. When thetransmitter detection coil 130 receives the first AC voltage signal 134,the frequency counter 208 determines the frequency of the first ACvoltage signal 134, while the peak detector 210 determines the voltageof the first AC voltage signal 134. In one embodiment, the peak detector210 measures the peak voltage of the first AC voltage signal 134.

Further, the control unit 112 compares the determined characteristicswith pre-stored characteristics. More specifically, the control unit 112may include a look-up table 212 having the pre-stored characteristics ofone or more receiver devices. In one embodiment, the characteristics mayinclude frequency and voltage values of the receiver device 104. If thedetermined characteristics is same or proximate to the pre-storedcharacteristics, the control unit 112 detects the presence of thereceiver device 104. In one embodiment, the control unit 112 may includeone or more comparators to compare the characteristics of the first ACvoltage signal 134 with the pre-stored characteristics. In oneembodiment, the control unit 112 may verify whether at least one of thecharacteristics is within a predefined range. More specifically, thecontrol unit 112 may determine whether the frequency of the first ACvoltage signal 134 is within a predefined frequency range. In anotherembodiment, the control unit 112 may determine whether the voltage ofthe first AC voltage signal 134 is within a predefined voltage range.

Further, the control unit 112 drives the driver unit 108 to transmitelectric power to the detected receiver device 104. In particular, thecontrol unit 112 sends one or more control signals to the driver unit108 to convert the DC voltage signal 118 from the power source 106 tothe second AC voltage signal 136. In one embodiment, the control unit112 may include a pulse width modulator (PWM) to send control signals tothe driver unit 108. In one embodiment, the driver unit 108 includes aplurality of electronic switches 214 that are arranged to form a bridgecircuit between first terminals 150 and second terminals 152 of thedriver unit 108. The switches 214 are activated and deactivated based onthe control signals received from the control unit 112 to convert the DCvoltage signal 118 to the second AC voltage signal 136. The frequency ofthe second AC voltage signal 136 is based on a frequency of the controlsignals transmitted to the driver unit 108. The frequency of the secondAC voltage signal 136 is selected based on a frequency standard of thedetected receiver device 104. In one embodiment, the first AC voltagesignal 134 received from the receiver device 104 may include frequencyinformation related to the frequency standard of the receiver device104. This frequency information may be used by the control unit 112 tooperate the driver unit 108 at a corresponding frequency fortransmitting the second AC voltage signal 136 to the receiver device104.

The resonant capacitor 115 and the power transmission coil 116 in thetransmitting unit 110 may resonate at a predefined frequency or aresonant frequency to transmit the second AC voltage signal 136 to thepower reception coil 124 in the receiver device 104. Further, the powerreception coil 124 and a resonant capacitor 125 in the receiver device104 transmits the received second AC voltage signal 136 to the rectifierunit 128. The rectifier unit 128 converts the second AC voltage signal136 to the DC load signal 144, which is further transmitted to the load126. In one embodiment, the rectifier unit 128 includes a plurality ofdiodes 216 that are arranged to form a bridge circuit. The rectifierunit is configured to convert the second AC voltage signal 136 to the DCload signal 144, which is further transmitted to the load 126. The DCload signal 144 may be used for charging the batteries in the receiverpower source 138.

Referring to FIG. 3, a flow chart illustrating a method 300 forindicating a presence of a receiver device and receiving electric powerfrom a wireless charging device in accordance with certain embodimentsof the present invention is depicted. At step 302, a signal generatingunit generates a first AC voltage signal having a characteristicassociated with a receiver device. In one example, the characteristicincludes a frequency and a voltage associated with the receiver device.In one embodiment, the signal generating unit generates the first ACvoltage signal when a push switch is manually pressed or switched ON bya user.

Subsequently, at step 304, the first AC voltage signal is transmitted toa wireless charging device. To that end, a receiver detection coil inthe receiver device transmits the first AC voltage signal having thecharacteristic to a transmitter detection coil in the wireless chargingdevice. In particular, the first AC voltage signal is transmitted to thewireless charging device to indicate the presence of the receiver deviceto the wireless charging device. In one embodiment, the receiver andtransmitter detection coils are used as dedicated coils forcommunicating signals that aid in detecting the receiver device.

At step 306, the input power having a second AC voltage signal isreceived in response to transmitting the first AC voltage signal fromthe receiver device to the wireless charging device. A power receptioncoil receives the second AC voltage signal from a power transmissioncoil of the wireless charging device. In particular, the detection unitdetermines one or more characteristics from the first AC voltage signalreceived from the receiver device. The characteristics may includefrequency and voltage values of the first AC voltage signal. Further,the control unit that is coupled to the detection unit, verifies whetherthe determined characteristics are within their correspondingpre-defined range. For example, the control unit may verify whether thefrequency of the first AC voltage signal is within a pre-definedfrequency range. Similarly, the control unit may determine whether thevoltage of the first AC voltage signal is within a pre-defined voltagerange.

Further, the control unit detects the receiver device, if thecharacteristics of the first AC voltage signal are within theircorresponding pre-defined range. The control unit activates the driverunit to transmit electric power to the receiver device. In oneembodiment, the control unit sends one or more control signals to thedriver unit to convert the DC voltage signal to the second AC voltagesignal. Further, the converted second AC voltage signal is transmittedto the receiver device via the power transmission coil.

The second AC voltage signal is received by the power reception coil inthe receiver device. Further, the rectifier unit coverts this second ACvoltage signal to a DC load signal for charging the load, such as one ormore batteries in the receiver device.

FIG. 4 is a flow chart illustrating a method 400 for detecting areceiver device in accordance with embodiments of the present invention.At step 402, a first AC voltage signal having a characteristicassociated with the receiver device is received by a transmitterdetection coil of a wireless charging device. In one example, thecharacteristic includes a frequency and a voltage associated with thereceiver device. In another example, the characteristic may berepresentative of a frequency and/or a voltage associated with thereceiver device. In particular, the transmitter detection coil ismagnetically coupled to a receiver detection coil in the receiverdevice. Further, the transmitter detection coil receives the first ACvoltage signal from the receiver detection coil.

Subsequently, at step 404, the receiver device is detected by a controlunit based on the characteristic of the first AC voltage signal. Morespecifically, if the receiver device is within the predetermineddistance from the wireless charging device, the characteristics, such asthe frequency and the voltage of the first AC voltage signal are withincorresponding predefined range. Specifically, the frequency of the firstAC voltage signal is within a predefined frequency range and the voltageof the received first AC voltage signal is within a predefined voltagerange, if the receiver device is within the predetermined distance fromthe charging device. If the characteristics, such as the frequency andthe voltage of the first AC voltage signal are within the correspondingrange, the control unit determines that the receiver device is proximateor within the predetermined distance from the charging device.

Furthermore, at step 406, a DC voltage signal of an input power isconverted to a second AC voltage signal by a driver unit if the receiverdevice is detected. In particular, if the receiver device is detected,the control unit transmits one or more control signals to the driverunit to convert the DC voltage signal from the power source to thesecond AC voltage signal.

In addition, at step 408, the second AC voltage signal is wirelesslytransmitted to the receiver device by a power transmission coil. Morespecifically, a resonant capacitor and the power transmission coil inthe transmitting unit may resonate at a predefined frequency or aresonant frequency to transmit the second AC voltage signal to a powerreception coil in the receiver device. Further, the power reception coiland a resonant capacitor in the receiver device transmits the receivedsecond AC voltage signal to the rectifier unit. The rectifier unitconverts the second AC voltage signal to the DC load signal, which isfurther transmitted to the load.

In accordance with the exemplary embodiments discussed herein, theexemplary system and method facilitate to detect the receiver device. Inparticular, the system and method disclosed herein allow chargingdevices, such as power banks to transmit power only after detecting thereceiver device. As a result, power loss is reduced and efficiency ofthe charging devices is enhanced. Further, the exemplary system andmethod disclosed herein enable detection of any foreign objects.Further, the exemplary system and method facilitate to reduceelectromagnetic interference (EMI) and thereby meet regulatorystandards.

While only certain features of the present disclosure have beenillustrated and described herein, many modifications and changes willoccur to those skilled in the art. It is, therefore, to be understoodthat the appended claims are intended to cover all such modificationsand changes as fall within the true spirit of the present disclosure.

1. A wireless charging device (102) comprising: a transmitter detectioncoil (130) configured to receive a first alternating current (AC)voltage signal having a characteristic associated with a receiver device(104); a control unit (112) coupled to the transmitter detection coil(130) and configured to detect the receiver device (104) based on thecharacteristic of the first AC voltage signal; a driver unit (108)coupled to the control unit (112) and configured to convert a directcurrent (DC) voltage signal of an input power to a second AC voltagesignal if the receiver device (104) is detected; and a powertransmission coil (116) coupled to the driver unit (108) and configuredto wirelessly transmit the second AC voltage signal to the receiverdevice (104).
 2. The wireless charging device (102) of claim 1, furthercomprising a power source (106) configured to transmit the input powerhaving the DC voltage signal to the driver unit (108).
 3. The wirelesscharging device (102) of claim 1, further comprising a detection unit(114) coupled to the transmitter detection coil (130) and configured todetermine the characteristic of the first AC voltage signal, wherein thecharacteristic of the first AC voltage signal is representative of atleast one of a frequency and a voltage associated with the receiverdevice (104).
 4. The wireless charging device (102) of claim 3, whereinthe control unit (112) is configured to detect the receiver device (104)if the frequency of the first AC voltage signal is within a predefinedfrequency range.
 5. The wireless charging device (102) of claim 3,wherein the control unit (112) is configured to detect the receiverdevice (104) if the voltage of the first AC voltage signal is within apredefined voltage range.
 6. The wireless charging device (102) of claim3, wherein the control unit (112) is configured to: compare thecharacteristic of the first AC voltage signal with a pre-storedcharacteristic; and detect the receiver device (104) if thecharacteristic of the first AC voltage signal is same or proximate tothe pre-stored characteristic.
 7. The wireless charging device (102) ofclaim 1, wherein the control unit (112) is configured to activate thedriver unit (108) to transmit the second AC voltage signal after thereceiver device (104) is detected.
 8. A receiver device (104)comprising: a signal generating unit (140) configured to generate afirst alternating current (AC) voltage signal having a characteristicassociated with the receiver device (104); a receiver detection coil(132) coupled to the signal generating unit (140) and configured totransmit the first AC voltage signal having the characteristic to awireless charging device (102); and a power reception coil (124)configured to be magnetically coupled to the wireless charging device(102) and receive input power having a second AC voltage signal inresponse to transmitting the first AC voltage signal to the wirelesscharging device (102).
 9. The receiver device (104) of claim 8, furthercomprising a rectifier unit (128) coupled to the power reception coil(124) and configured to convert the second AC voltage signal to a directcurrent (DC) load signal to charge at least one load (126).
 10. Thereceiver device (104) of claim 9, further comprising a receiver powersource (138) coupled to the signal generating unit (140) and configuredto transmit a bias voltage to the signal generating unit (140) togenerate the first AC voltage signal, wherein the receiver power source(138) is charged by the DC load signal received from the wirelesscharging device (102).
 11. The receiver device (104) of claim 8, furthercomprising a push switch (142) coupled to the signal generating unit(140) and configured to activate the signal generating unit (140). 12.The receiver device (104) of claim 8, wherein the characteristic of thefirst AC voltage signal is representative of at least one of a frequencyand a voltage associated with the receiver device (104).
 13. A methodcomprising: generating, by a signal generating unit (140), a firstalternating current (AC) voltage signal having a characteristicassociated with a receiver device (104); transmitting, by a receiverdetection coil (132), the first AC voltage signal having thecharacteristic to a wireless charging device (102); and receiving, by apower reception coil (124), input power having a second AC voltagesignal in response to transmitting the first AC voltage signal to thewireless charging device (102).
 14. The method of claim 13, furthercomprising converting, by a rectifier unit (128), the second AC voltagesignal to a DC load signal to charge at least one load (126).
 15. Themethod of claim 14, further comprising supplying, by a receiver powersource (138), a bias voltage to the signal generating unit (140) togenerate the first AC voltage signal.
 16. A wireless power transfersystem comprising: at least one receiver device (104) comprsing: asignal generating unit (140) configured to generate a first alternatingcurrent (AC) voltage signal having a characteristic associated with theat least one receiver device (104); a receiver detection coil (132)coupled to the signal generating unit (140) and configured to transmitthe first AC voltage signal having the characteristic to a wirelesscharging device (102); the wireless charging device (102) wirelesslycoupled to the at least one receiver device (104) and comprising: atransmitter detection coil (130) configured to receive the firstalternating current (AC) voltage signal having the characteristicassociated with the receiver device (104); and a control unit (112)coupled to the transmitter detection coil (130) and configured to detectthe receiver device (104) based on the characteristic of the first ACvoltage signal.
 17. The wireless power transfer system of claim 16,wherein the wireless charging device (102) further comprises: a driverunit (108) coupled to the control unit (112) and configured to convert adirect current (DC) voltage signal of an input power to a second ACvoltage signal if the receiver device (104) is detected; and a powertransmission coil (116) coupled to the driver unit (108) and configuredto wirelessly transmit the second AC voltage signal to the receiverdevice (104).
 18. The wireless power transfer system of claim 17,wherein the at least one receiver device (104) further comprises: apower reception coil (124) configured to be magnetically coupled to thewireless charging device (102) and receive input power having the secondAC voltage signal in response to transmitting the first AC voltagesignal to the wireless charging device (102); and a rectifier unit (128)coupled to the power reception coil (124) and configured to convert thesecond AC voltage signal to a direct current (DC) load signal to chargeat least one load (126).
 19. The wireless power transfer system of claim16, wherein the at least one receiver device (104) further comprises areceiver power source (138) coupled to the signal generating unit (140)and configured to transmit a bias voltage to the signal generating unit(140) to generate the first AC voltage signal.
 20. The wireless powertransfer system of claim 16, wherein the at least one receiver device(104) further comprises a push switch (142) coupled to the signalgenerating unit (140) and configured to activate the signal generatingunit (140).